This invention relates to systems and methods for remote actuation or control of tools and completion equipment in gas and oil wells, whether in subsurface or subsea locations, for communication and control in measurement while drilling (MWD) systems and associated tools, and for remote control of traveling bodies and stationary elements in pipeline installations.
As oil and gas drilling and production techniques have advanced and become more complex and versatile, many different downhole tools have come into use. Some include their own power packs, or other energy sources, and either are or can potentially be operated by remote control. Microprocessors, which are small, reliable and have low power consumption, are commonly used in such toots and equipment. There are many other potential applications for remote control of tools and other equipment within a confining passageway at a substantial distance, including not only in the drilling, completion, workover, production and abandonment of a well, but also in tools and devices that are fixed or movable in pipelines and further with underwater equipment connected to a surface system via a subsea manifold. If commands can reliably be communicated to a remote well bore location, then such functions as opening and closing valves, sliding sleeves, inflating plugs, detonating perforating guns, shifting tools and setting packers are available. Through the use of remote actuation, expensive down time in the well can be minimized, saving the costs of many hours or even days of operation.
Systems have been proposed, and some are in use, for remote control of equipment in well bore installations. A wire connection system using electric line has been in use for some time, and remains in use today. This system employs a heavy duty electrical line that is fed into the well bore along the tubing or casing string to the downhole location. The line is of relatively large diameter and for setup requires a massive carrier and support equipment, with setup time requiring many hours. Moreover, electrical power transmitted into a deep well creates potential dangers from short circuits and arcing in explosive environments at the well site where an inert atmosphere cannot be maintained. A later developed xe2x80x9cSlicklinexe2x80x9d is only a wire for providing mechanical operations and is of much smaller diameter although very high strength. While it can be transported and manipulated by much smaller vehicles and installations, and is deployed considerable more rapidly than the electric line mechanism, it is not well suited to remote operation of downhole tools. Time consuming and unsafe control methods with these systems are based on use of time and motion sequences combined with pressure and temperature readings.
Other systems are known for transmitting non-electrical commands to preinstalled downhole tools by communicating through a pressurized liquid medium or metal walls along the well bore. Pressure variations imparted at the surface of the liquid column are sensed by a strain gauge or other transducer at the remote location, to trigger a battery powered device in response to a coded pressure varying signal. One such system, called the xe2x80x9cEDGExe2x80x9d (trademark of Baker Hughes) system, interfaces with liquid media only and injects pulses of chosen frequency into the well bore. A downhole tool having an actuatable element powered at the tool includes electronic circuits which filter the selected frequency from other variations and responds to a selected pattern of pulse frequencies. This system requires substantial setup time and can only be used in a constant and predictable liquid filled bore. Another system effects control of mechanical devices by establishing a high initial pressure and then bleeding off pressure in a programmed fashion.
There is a need, therefore, for a remote control system and method which will function reliably in actuating a remote tool or other equipment, whatever the nature of the media in the confining elongated bore. Preferably, it should be useful in a wide range of well drilling and completion operations, including MWD, and in pipeline applications. The system and method should ensure against accidental triggering of the remote device and be essentially insensitive to extraneous operating conditions and effects. It should also be capable of remote control of selected individual ones of a number of different devices, and providing redundant modes of detection for enhanced reliability and communication capability. While retaining the higher degree of reliability, the system should preferably also require substantially less setup and operating time for field installation and actuation.
MWD installations currently in use require communication with bottom hole assembly (BHA) measuring equipment such as sensors, instruments and microprocessors. The MWD equipment stores information on many parameters including but not limited to bit direction, hole angle, formation evaluation, pressure, temperature, weight on bit, vibration and the like. This is transmitted to the surface using mud pulsing technology. Communicating to the MWD equipment for the purpose of controlling movable elements (i.e. to adjust the stabilizer blades to control direction) is, however, another matter, since not only must commands be given, but they must actuate the proper tool and provide sufficient data to make a quantitative adjustment. The current methods use changes of pump rate, and changes or weight on the bit, both of which take time, are limited in data rate, and increase the chances of sticking the drill string.
Remote control of elements in pipelines is a significant objective, since pipeline pigs are driven downstream for inspection or cleaning purposes and can stick or malfunction. Some pigs include internal processor and control equipment while others are designed to disintegrate under particular conditions. The ability to deliver commands to a pig or a stationary device in a remote location in a pipeline is thus highly desirable.
The present invention disclosed herein utilizes low frequency, brief pressure impulses of a few cycles duration and very high midterm amplitude to propagate into and through media of different types in a tubular system. The impulse energy transforms during propagation into a time-stretched waveform, still at low frequency, that retains sufficient energy at great depth, so that it is readily detectable by modern pressure and motion responsive instruments.
The system and method provide for communication in the tubular system between a transmission node, where the pressure impulses are generated, and a reception node, at a remote location. The system and method may be used, for example, to actuate a remote tool. The system comprises a transmission apparatus located at the transmission node. The transmission apparatus is in communication with a compressible media such that the transmission apparatus may generate pressure impulses in the media in the tubular system. The system also comprises a reception apparatus that detects the pressure impulses in the media at the reception node in or associated with the tubular system.
The transmission apparatus may generate either positive pressure impulses wherein at least one incremental pressure increase followed by at least one corresponding incremental pressure decrease is propagated through the media, or negative pressure impulses wherein at least one incremental pressure decrease followed by at least one corresponding incremental pressure increase is propagated through the media.
The reception apparatus of the present invention may include sensors for detecting impulse influences or impulse effects, namely variations in the characteristics of the media or the tubular system at the reception node. For example, the reception apparatus may detect variations in the pressure, displacement, velocity, acceleration or fluid density of the media or may detect variations in the longitudinal or circumferential stress, displacement, velocity or acceleration of the tubular system at the reception node. Alternatively, a combination of the above reception apparatuses may be used in redundant and mutually supportive fashion. This redundant capability assures against accidental triggering or actuation of the remote tool. Impact forces and pressures generated mechanically or transmitted from other sources through the surrounding environment are thus unlikely to affect the remote tool.
When the system and method of the present invention are utilized to actuate a remote tool, an actuation signal is generated by the reception apparatus in response to the detection of a pressure impulse. Optionally, a plurality of pressure impulses in a predetermined pattern may be generated and then compared to information stored in a control system for the remote tool to determine whether the pattern of impulses is intended to actuate that remote tool.
The system and method of the present invention thus impart a pressure impulse with sufficient energy to assure propagation along the tubular system to deep target locations. The received pressure impulses are so modulated and distinct as to provide a suitable basis for redundant transmissions, ensuring reliability. The system is tolerant of the complex media variations that can exist along the path within the well bore. Differences in wave propagation speed, tube dimension, and attenuation do not preclude adequate sensitivity and discrimination from noise. Further, using adequate impulse energy and distributed detection schemes, signals can reach all parts of a deephole installation having multiple lateral bores.
In a pipeline installation, the system and method of the present invention are particularly effective because with the uniform media in the pipeline, an impulse can traverse a long distance. Thus, an instrumented or cleaning pig can be commanded from a remote source to initiate a chosen control action or pig disintegration.
The system and method of the present invention are particularly suitable for MWD applications, which include not only directional controls, but utilize other commands to modify the operation of downhole units. The MWD context may utilize the pressure impulse encoding capabilities of the present invention to compensate for the dynamic-variations that are encountered by the MWD equipment during operation.
The system and method are also applicable to subsea oil and gas production installations, which typically interconnect a surface platform or vessel via pipelines to a seafloor manifold system communicating with subterranean well bores. By transmitting pressure impulses from the surface, systems on the seafloor and downhole tools can be addressed and controlled via the pipelines.